1. Field of the Invention
The subject invention relates to a thermosiphon cooling assembly for cooling an electronic device.
2. Description of the Prior Art
The operating speed of computers is constantly being improved to create faster computers. With this, comes increased heat generation and a need to effectively dissipate heat.
Heat exchangers and heat sink assemblies have been used that apply natural or forced convection cooling methods to dissipate heat from electronic devices that are highly concentrated heat sources such as microprocessors and computer chips. These heat exchangers typically use air to directly remove heat from the electronic devices; however air has a relatively low heat capacity. Thus, liquid-cooled units called LCUs employing a cold plate in conjunction with high heat capacity fluids have been used to remove heat from these types of heat sources. Although LCUs are satisfactory for moderate heat flux, increasing computing speeds have required more effective heat sink assemblies.
Accordingly, thermosiphon cooling units (TCUs) have been used for cooling electronic devices having a high heat flux. A typical TCU absorbs heat generated by the electronic device by vaporizing the working fluid housed on the boiler plate of the unit. The boiling of the working fluid of the TCU is considered to be a two-phase fluid. The vapor generated during boiling of the working fluid is then transferred to a condenser, where it is liquefied by the process of film condensation over the condensing surface of the TCU. The heat is rejected into a stream of air flowing through a tube running through the condenser or flowing over fins extending from the condenser. Alternatively, a second refrigerant can flow through the tube increasing the cooling efficiency. The condensated liquid is returned back to the boiler plate by gravity to continue the boiling-condensing cycle.
An example of a cooling system for electronic devices is disclosed in U.S. Pat. No. 6,834,713 to Ghosh et al.
The Ghosh patent discloses an assembly for cooling an electronic device including a boiler plate presenting an interior surface for transferring heat from the electronic device. A refrigerant is disposed in a boiler housing that extends from the boiler plate and parallel to the boiler plate to define a boiling chamber over the interior surface of the boiler plate. Heat generated by the electronic device dissipates into the housing through the boiler plate causing the refrigerant to boil. The cover of the boiler housing defines a plurality of openings to allow the vapor boiled off the refrigerant to escape from the boiling chamber. A plurality of hairpin condenser tubes presenting spaced legs extend into the openings of the boiler housing for collection of refrigerant vapor. A plurality of fins extend transversely to the legs of the hairpin tubes for transferring heat from the hairpin tubes.
Although the prior art dissipates heat from electronic devices, as computing speeds increase, there is a continuing need for cooling devices having more efficient or alternative heat transfer capabilities as compared to the known electronic cooling assemblies.